Near-infrared shielding material fine particle dispersion body, near-infrared shielding body and near-infrared shielding laminated structure, and method for producing the same

ABSTRACT

A near-infrared shielding material fine particle dispersion body, a near-infrared shielding body, and a near-infrared shielding laminated structure containing composite tungsten oxide that exhibits more excellent near-infrared shielding function than that of a conventional near-infrared shielding material fine particle dispersion body, near-infrared shielding body, and near-infrared shielding laminated structure, and a method for producing the same. Also, a near-infrared shielding material fine particle dispersion body in which near-infrared shielding material fine particles are dispersed in a solid medium. The near-infrared shielding material fine particles are composite tungsten oxide fine particles containing a hexagonal crystal structure, in which a lattice constant of the composite tungsten oxide fine particles is 7.3850 Å or more and 7.4186 Å or less on the a-axis, and 7.5600 Å or more and 7.6240 Å or less on the c-axis, and a particle size of the near-infrared shielding material fine particles is 100 nm or less.

TECHNICAL FIELD

The present invention relates to a near-infrared shielding material fineparticle dispersion body, a near-infrared shielding body, and anear-infrared shielding laminated structure which are transparent in avisible light region and have absorption in a near-infrared region, anda method for producing the same.

DESCRIPTION OF RELATED ART

As a light shielding member used for a window material or the like,patent document 1 proposes a light shielding film containing a blackpigment containing inorganic pigments such as carbon black and titaniumblack having absorption in a visible light region to a near-infraredlight region, and organic pigments such as aniline black having strongabsorption only in the visible light region, and patent document 2proposes a half mirror type light shielding member having metal such asaluminum vapor-deposited thereon.

Patent document 3 proposes a heat ray shielding glass which can besuitably used in a site requiring high visible light transmittance andgood heat ray shielding performance, in which a composite tungsten oxidefilm is provided on a transparent glass substrate as a first layer froma substrate side, the composite tungsten oxide film containing at leastone metal ion selected from the group consisting of IIa group, IVagroup, Vb group, VIb group and VIIb group of a periodic table, and atransparent dielectric film is provided on the first layer as a secondlayer, and a composite tungsten oxide film is provided on the secondlayer as a third layer, the composite tungsten oxide film containing atleast one metal ion selected from the group consisting of IIIa group,IVa group, Vb group, VIb group and VIIb group of the periodic table, anda refractive index of the transparent dielectric film of the secondlayer is made lower than the refractive index of the composite tungstenoxide film of the first layer and the third layer.

Patent document 4 proposes a heat ray shielding glass in which a firstdielectric film is provided on a transparent glass substrate as a firstlayer from a substrate side, and a tungsten oxide film is provided onthe first layer as a second layer, and a second dielectric film isprovided on the second layer as a third layer, in the same manner as inpatent document 3.

Patent document 5 proposes a heat ray shielding glass in which acomposite tungsten oxide film containing the same metal element isprovided on a transparent substrate from a substrate side as a firstlayer, and a transparent dielectric film is provided on the first layeras a second layer, in the same manner as in patent document 3.

Patent document 6 proposes a sunlight shielding glass sheet having asunlight shielding property, which is formed by coating thereon a metaloxide film selected from one or more kinds of tungsten trioxide (WO₃),molybdenum trioxide (MoO₃), niobium pentoxide (Nb₂O₅), tantalumpentoxide (Ta₂O₅), vanadium pentoxide (V₂O₅) and vanadium dioxide (VO₂)containing additives such as hydrogen, lithium, sodium or potassium, bya CVD method or a spraying method, and thermally decomposing at about250° C.

Patent document 7 proposes to obtain a sunlight modulating lightinsulating material whose coloring and decoloring reaction to sunlightis fast, having an absorption peak at a wavelength of 1250 nm in thenear-infrared region at the time of coloring, and capable of blockingnear-infrared rays of sunlight, by using tungsten oxide obtained byhydrolyzing tungsten acid, and using the following properties: when anorganic polymer having a specific structure called polyvinyl pyrrolidoneis added to the tungsten oxide and when irradiated with sunlight,ultraviolet rays in the sunlight are absorbed by the tungsten oxide, andexcited electrons and holes are generated, thereby causing remarkableincrease in an amount of pentavalent tungsten due to a small amount ofultraviolet ray, and as the coloring reaction becomes faster, coloringdensity becomes higher, and pentavalent tungsten is extremely promptlyoxidized to hexavalent by blocking light, resulting in faster decoloringreaction.

The present inventors propose in patent document 8 the following points:powder composed of tungsten trioxide or a hydrate thereof or a mixtureof both is obtained by dissolving tungsten hexachloride in alcohol andevaporating the solvent as it is, or by evaporating the solvent afterheating under reflux and then applying heating at 100° C. to 500° C.; anelectrochromic device is obtained using the tungsten oxide fineparticles; and the optical properties of the film can be changed when amultilayer laminate is formed and protons are introduced into the film.

Patent document 9 proposes a method for making various tungsten bronzesexpressed by M_(x)WO₃ (M element is a metal element such as alkali,alkaline earth, rare earth, and satisfying 0<x<1), by using meta-typeammonium tungstate and various water-soluble metal salts as rawmaterials, and by supplying a hydrogen gas added with an inert gas(addition amount: about 50 vol % or more) or steam (added amount: about15 vol % or less) to a dry matter of the above mixed aqueous solution,while heating to about 300 to 700° C.

The present inventors disclose an infrared shielding material fineparticle dispersion body in which infrared material fine particles aredispersed in a medium, wherein the infrared material fine particlescontain tungsten oxide fine particles or/and composite tungsten oxidefine particles, and a dispersed particle size of the infrared materialfine particle is 1 nm or more and 800 nm or less.

PRIOR ART DOCUMENT Patent Document

[Patent Document 1] Japanese Patent Application Laid-Open No.2003-029314

[Patent Document 2] Japanese Patent Application Laid-Open No.1997-107815

[Patent Document 3] Japanese Patent Application Laid-open No. 1996-59300

[Patent Document 4] Japanese Patent Application Laid-Open No. 1996-12378

[Patent Document 5] Japanese Patent Application Laid-Open No.1996-283044

[Patent Document 6] Japanese Patent Application Laid-Open No.2000-119045

[Patent Document 7] Japanese Patent Application Laid-Open No.1997-127559

[Patent Document 8] Japanese Patent Application Laid-Open No.2003-121884

[Patent Document 9] Japanese Patent Application Laid-Open No. 1996-73223

[Patent Document 10] International Publication WO 2005/037932

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

However, according to the study of the inventors of the presentinvention, it is found that proposals and disclosures described inpatent documents 1 to 10 have the following problems.

The black pigment described in patent document 1 has large absorption inthe visible light region. Accordingly, a color tone of a window materialetc. to which the black pigment is applied becomes darker, and thereforeit is considered that a use method is limited.

A window material or the like to which a metal vapor deposition filmdescribed in patent document 2 is applied, has a half-mirror appearance.Therefore, when the window material or the like to which the metal vapordeposition film is applied, is used outdoors, it is considered thatreflection is dazzling and there is a problem in terms of a landscape.

Heat ray shielding materials described in patent documents 3 to 5 aremainly produced by a method using a dry method by a vacuum film formingmethod such as a sputtering method, a vapor deposition method, an ionplating method and a chemical vapor deposition method (CVD method).Therefore, there is a problem that a large-sized production device isrequired and a production cost is increased.

Further, a base material of the heat ray shielding material is exposedto high temperature plasma or heating after film formation is necessary.For this reason, when using a resin such as a film as a substrate, it isnecessary to additionally investigate the film formation conditions onthe equipment.

In addition, the tungsten oxide film and the composite tungsten oxidefilm described in these patent documents 3 to 5, are the films thatexhibit a predetermined function when a multilayer film with anothertransparent dielectric film is formed, and therefore it is considered tobe different from the present invention.

A sunlight-controlled coated glass sheet described in patent document 6is formed as a film on a glass by a CVD method, or a combination of aspray method and a thermal decomposition method. However, there arelimitations such as expensive raw materials to be a precursor andthermal decomposition at high temperature, and therefore in the case ofusing the resin such as a film as a base material, it is necessary toseparately investigate the film formation conditions. Further, this filmis a film that exhibits a predetermined function when forming amultilayer film of two or more layers and it is considered that this isa different proposal from the present invention.

The sunlight modulatable light heat insulating material and anelectrochromic device described in patent documents 7 to 8, arematerials that change the color tone of the film due to ultraviolet raysor a potential difference, and therefore it is considered that they arehardly applied to a field of application where a film structure iscomplicated and change in color tone is not desired.

Patent document 9 describes a method for producing tungsten bronze.However, this document does not describe a particle size and opticalproperties of the obtained powder. This is because in this document, itis considered that the tungsten bronze is used as an electrode materialof an electrolytic device, a fuel cell, or a catalytic material oforganic synthesis. Namely, it is considered that this is a differentproposal from the present invention.

Patent Document 10 is made to solve the above-described problem, andprovides the near-infrared shielding material fine particles, anear-infrared shielding material fine particle dispersion body, anear-infrared shielding body, and near-infrared shielding material fineparticles that sufficiently transmit a visible light, does not have ahalf mirror-like appearance, not requiring a large-scale productiondevice for film formation on a substrate, not requiring high temperatureheat treatment at the time of film formation, and meanwhile, efficientlyshielding invisible near-infrared rays having a wavelength of 780 nm ormore, and transparent with no change of color tone, and provides amethod for producing the same. However, a market demand for anear-infrared shielding function of the near-infrared shielding bodycontinues to increase, and it is considered difficult to continue tosatisfy the requirements of the market even with the tungsten oxide fineparticles or/and the composite tungsten oxide fine particles describedin patent document 10.

Under the above-described circumstance, and in order to solve theproblem, the present invention is provided, and an object of the presentinvention is to provide a near-infrared shielding material fine particledispersion body, a near-infrared shielding body, and a near-infraredshielding laminated structure containing composite tungsten oxide thatexhibits an effect of maintaining an effect of maintaining a hightransmittance in a visible light region while shielding a light in anear-infrared region more efficiently than a conventional near-infraredshielding material fine particle dispersion body, near-infraredshielding body, and near-infrared shielding laminated structurecontaining tungsten oxide or composite tungsten oxide.

Means for Solving the Problem

In order to solve the above-describe problem, the present inventorsconducted research.

Generally, it is known that a material containing free electronsexhibits a reflection absorption response to an electromagnetic wave dueto plasma vibration, the electromagnetic wave having a wavelength of 200nm to 2600 nm which is around a region of sunlight. Then, when thepowder of the material is fine particles smaller than a wavelength oflight, it is known that geometric scattering in the visible light region(wavelength 380 nm to 780 nm) is reduced, and transparency in thevisible light region is obtained. In the present invention, the term“transparency” is used in the meaning that scattering is small andtransparency is high to the light in the visible light region.

On the other hand, it is known that the tungsten oxide expressed by ageneral formula W_(3-x) or a so-called tungsten bronze obtained byadding a positive element such as Na to tungsten trioxide is aconductive material and is a material having free electrons. Then, inthese materials, a response of free electrons to light in the infraredregion is suggested by analysis of single crystal, etc.

The present inventors found the following configuration of the compositetungsten oxide fine particles which are near-infrared shielding materialfine particles: the crystals contained therein are hexagonal and alattice constant of the composite tungsten oxide fine particles is7.3850 Å or more and 7.4186 Å or less on the a-axis, and 7.5600 Å ormore and 7.6240 Å or less on the c-axis, and a particle size of thenear-infrared shielding material fine particles is 100 nm or less.

Namely, in order to solve the above-described problem, a first inventionis a near-infrared shielding material fine particle dispersion body inwhich near-infrared shielding material fine particles are dispersed in asolid medium,

wherein the near-infrared shielding material fine particles arecomposite tungsten oxide fine particles containing a hexagonal crystalstructure,

a lattice constant of the composite tungsten oxide fine particles is7.3850 Å or more and 7.4186 Å or less on the a-axis, and 7.5600 Å ormore and 7.6240 Å or less on the c-axis, and a particle size of thenear-infrared shielding material fine particles is 100 nm or less.

A second invention is the near-infrared shielding material fine particledispersion body according to the first invention, wherein the latticeconstant of the composite tungsten oxide fine particles is 7.4031 Å ormore and 7.4111 Å or less on the a-axis, and 7.5891 Å or more and 7.6240Å or less on the c-axis.

A third invention is the near-infrared shielding material fine particledispersion body according to the first invention, wherein the latticeconstant of the composite tungsten oxide fine particles is 7.4031 Å ormore and 7.4186 Å or less on the a-axis, and 7.5830 Å or more and 7.5950Å or less on the c-axis.

A fourth invention is the near-infrared shielding material fine particledispersion body, wherein the particle size of the near-infraredshielding material fine particles is 10 nm or more and 100 nm or less.

A fifth invention is the near-infrared shielding material fine particledispersion body, wherein the composite tungsten oxide fine particles areexpressed by a general formula M_(x)W_(y)O_(z) (wherein M element is oneor more elements selected from the group consisting of H, He, alkalimetal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru,Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn,Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi,and I, W is tungsten, O is oxygen, and satisfying 0.20≤x/y≤0.37, and2.2≤z/y≤3.0.).

A sixth invention is the near-infrared shielding material fine particledispersion body, wherein the M element is one or more elements selectedfrom Cs and Rb.

A seventh invention is the near-infrared shielding material fineparticle dispersion body, wherein a surface of each near-infraredshielding material fine particle is coated with an oxide containing oneor more elements selected from Si, Ti, Zr and Al.

An eighth invention is the near-infrared shielding material fineparticle dispersion body, wherein the solid medium is resin or glass.

A ninth invention is the near-infrared shielding material fine particledispersion body, wherein the resin is one or more kinds selected frompolyethylene resin, polyvinyl chloride resin, polyvinylidene chlorideresin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin,ethylene vinyl acetate copolymer, polyester resin, polyethyleneterephthalate resin, fluororesin, acrylic resin, polycarbonate resin,polyimide resin, and polyvinyl butyral resin.

A tenth invention is a near-infrared shielding body, wherein thenear-infrared shielding material fine particle dispersion body of anyone of the first to ninth inventions is formed into any one selectedfrom a plate shape, a film shape, and a thin film shape.

An eleventh invention is a near-infrared shielding laminated structure,wherein the near-infrared shielding material fine particle dispersionbody of any one of the first to ninth inventions is present between twoor more laminated plates selected from a plate glass, a plastic plate,and a plastic plate containing fine particles having a solar radiationshielding function.

A twelfth invention is a method for producing a near-infrared shieldingmaterial fine particle dispersion body, including:

a first step of producing composite tungsten oxide containing ahexagonal crystal structure expressed by a general formulaM_(x)W_(y)O_(z) (wherein M element is one or more elements selected fromthe group consisting of H, He, alkali metal, alkaline earth metal, rareearth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag,Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te,Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O isoxygen, and satisfying 0.20≤x/y≤0.37, and 2.2≤z/y≤3.0.);

a second step of producing composite tungsten oxide fine particles bymechanically pulverizing the composite tungsten oxide obtained in thefirst step, in which a lattice constant in the hexagonal crystalstructure is 7.3850 Å or more and 7.4186 Å or less on the a-axis, and7.5600 Å or more and 7.6240 Å or less on the c-axis, and a particle sizeis 100 nm or less; and

a third step of dispersing in a solid medium the composite tungstenoxide fine particles obtained in the second step, to obtain anear-infrared shielding material fine particle dispersion body.

A thirteenth invention is the method for producing a near-infraredshielding material fine particle dispersion body according to thetwelfth invention, wherein in the second step, composite tungsten oxidefine particles are produced, in which the lattice constant in thehexagonal crystal structure is 7.4031 Å or more and 7.4111 Å or less onthe a-axis and 7.5891 Å or more and 7.6240 Å or less on the c-axis, andthe particle size is 100 nm or less.

A fourteenth invention is the method for producing a near-infraredshielding material fine particle dispersion body according to thetwelfth invention, wherein in the second step, composite tungsten oxidefine particles are produced, in which the lattice constant in thehexagonal crystal structure is 7.4031 Å or more and 7.4186 Å or less onthe a-axis and 7.5830 Å or more and 7.5950 Å or less on the c-axis, andthe particle size is 100 nm or less.

A fifteenth invention is the method for producing a near-infraredshielding material fine particle dispersion body, wherein the solidmedium is resin or glass.

A sixteenth invention is the method for producing a near-infraredshielding material fine particle dispersion body, wherein the resin isone or more kinds selected from polyethylene resin, polyvinyl chlorideresin, polyvinylidene chloride resin, polyvinyl alcohol resin,polystyrene resin, polypropylene resin, ethylene vinyl acetatecopolymer, polyester resin, polyethylene terephthalate resin,fluororesin, acrylic resin, polycarbonate resin, polyimide resin, andpolyvinyl butyral resin.

A seventeenth invention is the method for producing a near-infraredshielding material fine particle dispersion body, wherein the third stepfurther includes a fourth step of forming the near-infrared shieldingmaterial fine particle dispersion body into any one selected from aplate shape, a film shape, and a thin film shape.

An eighteenth invention is the method for producing a near-infraredshielding material fine particle dispersion body, wherein the fourthstep includes a step of forming the near-infrared shielding materialfine particle dispersion body on a substrate surface.

A nineteenth invention a method for producing a near-infrared shieldinglaminated structure, including a fifth step of sandwiching thenear-infrared shielding material dispersion body obtained in the methodfor producing a near-infrared shielding material fine particledispersion body of the seventeenth or eighteenth invention, between twoor more opposed transparent substrates selected from a sheet glass, aplastic, and a plastic containing fine particles having a solarshielding function.

Advantage of the Invention

The near-infrared shielding material fine particle dispersion body, thenear-infrared shielding body, and the near-infrared shielding laminatedstructure of the present invention exhibit excellent optical propertiessuch as maintaining a high transmittance in a visible light region whileshielding a light in a near-infrared region more efficiently than theconventional near-infrared shielding material fine particle dispersionbody, near-infrared shielding body and near-infrared shielding laminatedstructure.

DETAILED DESCRIPTION OF THE INVENTION

The near-infrared shielding material fine particle dispersion body ofthe present invention contains composite tungsten oxide fine particleshaving a hexagonal crystal structure, with near-infrared shieldingmaterial fine particles dispersed in a solid medium, in which a latticeconstant in a hexagonal crystal structure is 7.3850 Å or more and 7.4186Å or less on the a-axis and 7.5600 Å or more and 7.6240 Å or less on thec-axis, and a particle size is 100 nm or less.

Further, a near-infrared shielding laminated structure of the presentinvention is configured so that the near-infrared shielding materialfine particle dispersion body of the present invention is presentbetween two or more laminated plates selected from a plate glass, aplastic plate, and a plastic plate containing fine particles having asolar radiation shielding function.

The present invention will be described in detail hereafter, in an orderof 1. Near-infrared shielding material, 2. Method for producing nearinfrared shielding material fine particles, 3. Near-infrared shieldingmaterial fine particle dispersion liquid, 4. Near-infrared shieldingmaterial fine particle dispersion body, 5. Near-infrared shieldingeffect of the near-infrared shielding material fine particle dispersionbody, 6. Near-infrared shielding body, 7. Method for producingnear-infrared shielding material fine particle dispersion body andnear-infrared shielding body, 8. Near-infrared shielding laminatedstructure and method for producing the same, 9. Conclusion.

1. Near-Infrared Shielding Material

The near-infrared shielding material fine particles of the presentinvention are composite tungsten oxide fine particles having a hexagonalcrystal structure, and a lattice constant of the hexagonal compositetungsten oxide fine particles is 7.3850 Å or more and 7.4186 Å or lesson the a-axis, and 7.5600 Å or more and 7.6240 Å or less on the c-axis.Further, a value of the ratio (Lattice constant of c-axis/latticeconstant of a-axis) is preferably 1.0221 or more and 1.0289 or less.

Then, when the hexagonal composite tungsten oxide has theabove-described predetermined lattice constant, the near-infraredshielding material fine particle dispersion body in which the fineparticles are dispersed in the medium, exhibits a light transmittancehaving a maximum value in a wavelength range of 350 nm to 600 nm and aminimum value in a wavelength range of 800 to 2100 nm. Morespecifically, regarding the wavelength region where the maximum value ofthe transmittance occurs and the wavelength region where the minimumvalue occurs, the maximum value occurs in the wavelength range of 440 to600 nm, and the minimum value occurs in the wavelength range of 1150 to2100 nm. Namely, the maximum value of the transmittance occurs in thevisible light region, and the minimum value of the transmittance occursin the near-infrared region.

Detailed reasons why the near-infrared shielding material fine particlesof the present invention, in which the hexagonal composite tungstenoxide has the above-described predetermined lattice constant, exhibitexcellent optical properties are still under investigation. Here, thepresent inventors proceeded with research as follows and examined asfollows.

Generally, effective free electrons are not present in tungsten trioxide(WO₃), and therefore absorption and reflection properties in thenear-infrared region are small, and it is not effective as an infraredshielding material. Here, although it is known that free electrons aregenerated in the tungsten oxide by reducing the ratio of tungstentrioxide to tungsten to less than 3, it is found by the presentinventors that there is a particularly effective range as a range of anear-infrared shielding material in a specific portion of a compositionrange of tungsten and oxygen in the tungsten oxide.

Preferably, the composition range of tungsten and oxygen is such thatthe composition ratio of oxygen to tungsten is 3 or less, and furthersatisfies 2.2≤z/y≤2.999 when the tungsten oxide is expressed asW_(y)O_(z). This is because when the value of z/y is 2.2 or more, it ispossible to avoid the appearance of a crystal phase of WO₂ other than atarget in the tungsten oxide, and chemical stability as a material canbe obtained, and therefore the tungsten oxide can be used as aneffective near-infrared shielding material. Meanwhile, when the value ofz/y is 2.999 or less, a required amount of free electrons is generatedin the tungsten oxide, and it becomes an efficient near-infraredshielding material.

Further, the tungsten oxide fine particles in a state of finelygranulated tungsten oxide is expressed as a general formula W_(y)O_(z),a so-called “Magneli phase” having a composition ratio expressed by2.45≤z/y≤2.999 is chemically stable and has a good absorption propertyin the near-infrared region. Therefore, the tungsten oxide fineparticles are preferable as a near-infrared shielding material.

Further, it is also preferable to add M element to the tungsten oxide toform a composite tungsten oxide. This is because by adopting thisstructure, free electrons are generated in the composite tungsten oxide,and the absorption property derived from the free electrons appears inthe near-infrared region and therefore the composite tungsten oxide isalso effective as a near-infrared absorbing material in the vicinity of1000 nm in wavelength.

Here, from a viewpoint of stability in the composite tungsten oxide towhich the M element is added, M element is preferably one or moreelements selected from the group consisting of H, He, alkali metal,alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co,Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb,Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, andI.

By using both the control of the above-described oxygen amount andaddition of the element that generates free electrons for the compositetungsten oxide, a more efficient near-infrared shielding material can beobtained. When a general formula of the near-infrared shielding materialobtained by using both the control of the oxygen amount and the additionof the element that generates free electrons, is expressed as MxWyOz(wherein M element is the above-described M element, W is tungsten, andO is oxygen), the relation of 0.001≤x/y≤1, preferably 0.20≤x/y≤0.37 issatisfied.

Here, from a viewpoint of stability in the MxWyOz to which the M elementis added, M element is preferably one or more elements selected from thegroup consisting of alkali metal, alkaline earth metal, rare earthelement, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn,Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb,V, Mo, Ta, and Re. From a viewpoint of improving optical properties andweather resistance as the near-infrared shielding material, M elementbelonging to alkali metal, alkaline earth metal element, transitionmetal element, 4B group element, and 5B group element is morepreferable.

Next, the value of z/y showing the control of the oxygen amount will bedescribed. Regarding the value of z/y, a similar mechanism as thenear-infrared shielding material expressed by the above-described WyOzalso works on the near-infrared shielding material expressed by MxWyOz,and in addition, in a case of z/y=3.0, it is preferable to satisfy2.2≤z/y≤3.0 because there is supply of the free electrons due to theaddition amount of the M element.

Further, when the above-described composite tungsten oxide fineparticles have a hexagonal crystal structure, transmittance of the fineparticles in the visible light region is improved and the absorption ofthe fine particles in the near-infrared region is improved. In thishexagonal crystal structure, a hexagonal space (tunnel) is formed byassembling six octahedrons formed by units of WO₆, and the M element isarranged in the space to constitute one unit, and a large number of thisone unit gather to form a hexagonal crystal structure.

In order to obtain the effect of improving the transmission in thevisible light region and improving the absorption in the near-infraredregion of the present invention, a unit structure (structure in whichsix octahedrons formed by units of WO₆ gather to form a hexagonal spaceand the M element is disposed in the space) may be included in thecomposite tungsten oxide fine particles.

Absorption in the near-infrared region is improved when M elementcations are added to the hexagonal spaces and are present. Here,generally when M element having a large ionic radius is added, thehexagonal crystal structure is formed. Specifically, when one or moreelements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe and Sn areadded, the hexagonal crystal structure is likely to be formed, which ispreferable.

Further, in the composite tungsten oxide fine particles to which one ormore elements selected from Cs and Rb are added among the M elementshaving a large ionic radius, it is possible to achieve both of theabsorption in the near-infrared region and the transmission in thevisible light region.

In the case of Cs tungsten oxide fine particles in which Cs is selectedas the M element, its lattice constant is preferably 7.4031 Å or moreand 7.4186 or less on the a-axis and 7.5750 Å or more and 7.6240 Å orless on the c-axis.

In the case of Rb tungsten oxide fine particles in which Rb is selectedas the M element, its lattice constant is preferably 7.3850 Å or moreand 7.3950 or less on the a-axis and 7.5600 or more and 7.5700 Å or lesson the c-axis.

In the case of CsRb tungsten oxide fine particles in which Cs and Rb areselected as M elements, its lattice constant is preferably 7.3850 Å ormore and 7.4186 Å or less on the a-axis and 7.5600 Å or more and 7.6240Å or less on the c-axis.

However, the M element is not limited to the above Cs and Rb. Even ifthe M element is an element other than Cs or Rb, it may be present as anadded M element in the hexagonal spaces formed by units of WO₆.

When the composite tungsten oxide fine particles having a hexagonalcrystal structure have a uniform crystal structure, the addition amountof the M element to be added is 0.001≤x/y≤1, preferably 0.2≤x/y≤0.5,more preferably, 0.20≤x/y≤0.37, and most preferably x/y=0.33. This isbecause theoretically in a case of z/y=3, x/y=0.33 is established, andthe added M element is considered to be arranged in all the hexagonalspaces.

Here, the inventors of the present invention have made extensive studiesin consideration of further improving the near-infrared shieldingfunction of the composite tungsten oxide fine particles, and achieve astructure of increasing the amount of free electrons contained therein.

Namely, as a measure to increase the amount of free electrons, it isfound that a mechanical treatment is applied to the composite tungstenoxide fine particles to impart appropriate strain and deformation to thehexagonal crystal structure contained therein. In the hexagonal crystalstructure to which the appropriate strain or deformation is imparted, itis considered that an overlapping state of the electron orbitals in theatoms constituting the crystallite structure is changed and the amountof free electrons is increased.

Therefore, the present inventors study as follows: in the dispersingstep of producing the near-infrared shielding material fine particledispersion liquid from particles of the composite tungsten oxideproduced by the firing step, the composite tungsten oxide particles arepulverized under predetermined conditions to impart strain anddeformation to the crystal structure, thereby increasing the amount offree electrons to further improve the near-infrared shielding functionof the composite tungsten oxide fine particles.

From the study, attention was paid to each particle of the compositetungsten oxide particles produced through the firing step. Then, it isfound that variation is generated respectively in the lattice constantand the constituent element composition of each particle.

As a result of further study, it is found that desired opticalproperties are exhibited when the lattice constant of the ultimatelyobtained composite tungsten oxide fine particles is within apredetermined range, irrespective of the variation of the latticeconstant and constituent element composition among the particles.

The inventors who obtained the above knowledge further study on theoptical properties of the fine particles while grasping the degree ofstrain and deformation of the crystal structure of the fine particles,by measuring the lattice constant on the a-axis and on the c-axis in thecrystal structure of the composite tungsten oxide fine particles.

Then, as a result of the study, it is found that when the latticeconstant is 7.3850 Å or more and 7.4186 Å or less on the a-axis, and7.5600 Å or more and 7.6240 Å or less on the c-axis in the hexagonalcomposite tungsten oxide fine particles, the fine particles show atransmittance of a light having a maximum value in a wavelength range of350 nm to 600 nm, and a minimum value in the wavelength range of 800 nmto 2100 nm, and these fine particles are the near-infrared shieldingmaterial fine particles exhibiting an excellent near-infrared shieldingeffect. Thus, the present invention is completed.

Further, it is also found that in the hexagonal composite tungsten oxidefine particles of the near-infrared shielding material fine particlesaccording to the present invention having lattice constant of 7.3850 Åor more and 7.4186 Å or less on the a-axis, and 7.5600 Å or more and7.6240 Å or less on the c-axis, especially excellent near-infraredshielding effect is exhibited when the value of x/y showing the additionamount of the M element is within a range of 0.20≤x/y≤0.37.

Specifically, the near-infrared shielding material fine particledispersion body in which the near-infrared shielding material fineparticles of the present invention are dispersed in a solid medium andthe transmittance at a wavelength of 550 nm is 70% or more, shows atransmittance having a maximum value in the wavelength range of 350 nmto 600 nm and a minimum value in the wavelength range of 800 nm to 2100nm. Then, it is also found that in the near-infrared shielding materialfine particle dispersion body, when the maximum value and the minimumvalue of the transmittance are expressed as a percentage, and when thedifference between the maximum value (%) and the minimum value (%)≥69(points), namely, the difference between the maximum value and theminimum value is expressed as a percentage, especially an excellentoptical property of 69 points or more is exhibited.

Further, the near-infrared shielding material fine particles of thepresent invention have a particle size of 100 nm or less. Then, from aviewpoint of exhibiting further excellent infrared shielding properties,the particle size is preferably 10 nm or more and 100 nm or less, morepreferably 10 nm or more and 80 nm or less, further preferably 10 nm ormore and 60 nm or less, and most preferably 10 nm or more and 40 nm orless. When the particle size is in a range of 10 nm or more and 40 nm orless, the most excellent infrared shielding property is exhibited.

Here, the particle size is an average value of the diameters of theindividual near-infrared shielding material fine particles that are notaggregated, and an average particle size of the infrared shieldingmaterial fine particles contained in the near-infrared shieldingmaterial fine particle dispersion body described later.

Meanwhile, the particle size does not include the size of the aggregateof the composite tungsten oxide fine particles, and differs from thedispersed particle size.

The average particle size is calculated from an electron microscopeimage of the near-infrared shielding material fine particles.

The average particle size of the composite tungsten oxide fine particlescontained in the near-infrared shielding material fine particledispersion body can be obtained by measuring the particle size of 100composite tungsten oxide fine particles using an image processor andcalculating the average value thereof, from a transmission electronmicroscopic image of a thinned sample of the composite tungsten oxidefine particle dispersion body taken out by cross-sectional machining.For the cross-sectional machining for taking out the thinned sample, amicrotome, a cross-section polisher, a focused ion beam (FIB) device, orthe like can be used. Note that the average particle size of thecomposite tungsten oxide fine particles contained in the near-infraredshielding material fine particle dispersion body is the average value ofthe particle sizes of the composite tungsten oxide fine particlesdispersed in the matrix of the solid medium.

Further, from a viewpoint of exhibiting excellent infrared shieldingproperties, a crystallite size of the composite tungsten oxide fineparticles is preferably 10 nm or more and 100 nm or less, morepreferably 10 nm or more and 80 nm or less, further preferably 10 nm ormore and 60 nm or less, and most preferably 10 nm or more and 40 nm orless. This is because when the crystallite size is in a range of 10 nmor more and 40 nm or less, the most excellent infrared shieldingproperty is exhibited.

Note that the lattice constant and the crystallite size of the compositetungsten oxide fine particles contained in the composite tungsten oxidefine particle dispersion liquid obtained after a crushing treatment, apulverization treatment or a dispersion treatment, which will bedescribed later, are maintained in the composite tungsten oxide fineparticles obtained by removing volatile components from the compositetungsten oxide fine particle dispersion liquid, or in the compositetungsten oxide fine particles contained in the near-infrared shieldingmaterial fine particle dispersion body obtained from the compositetungsten oxide fine particle dispersion liquid.

As a result, the effect of the present invention is also exhibited inthe composite tungsten oxide fine particle dispersion liquid and thenear-infrared shielding material fine particle dispersion bodycontaining composite tungsten oxide fine particles of the presentinvention.

Further, the composite tungsten oxide fine particles as thenear-infrared shielding material fine particles, are preferable singlecrystals in which a volume ratio of the amorphous phase is 50% or less.

This is because when the composite tungsten oxide fine particles aresingle crystals in which the volume ratio of an amorphous phase is 50%or less, the crystallite size can be set to 10 nm or more and 100 nm orless, while maintaining the lattice constant within the above-describedpredetermined range.

In contrast, there is a case that the amorphous phase exists in a volumeratio of more than 50%, although the particle size of the compositetungsten oxide fine particles is 100 nm or less, or a case that thelattice constant cannot be maintained within the above-describedpredetermined range when the fine particles are polycrystalline. In thiscase, a transmittance maximum value of the light existing in awavelength range of 350 nm to 600 nm described above, and a minimumvalue of the light existing in a wavelength range of 800 nm to 2100 nmare expressed as a percentage, 69 points or more cannot be secured in adifference between the maximum value and the minimum value. As a result,the near-infrared absorption property becomes insufficient and thenear-infrared shielding property is insufficiently expressed.

It is confirmed that the composite tungsten oxide fine particle is asingle crystal, from the fact that in an electron microscopic image by atransmission electron microscope or the like, grain boundaries are notobserved in each fine particle, and only uniform lattice stripes areobserved. It is also confirmed that the volume ratio of the amorphousphase is 50% or less in the composite tungsten oxide fine particles,from the fact that uniform lattice stripes are observed throughout thefine particles, and almost no unclear places of the lattice stripes areobserved similarly in the transmission electron microscope image.

Further, the amorphous phase is frequently present in an outerperipheral portion of each fine particle, and therefore by payingattention to the outer peripheral portion of each fine particle, thevolume ratio of the amorphous phase can be calculated in many cases. Forexample, in a case of a spherical composite tungsten oxide fineparticle, when an amorphous phase whose lattice stripes are unclear ispresent in a layered manner on the outer peripheral portion of the fineparticle, the volume ratio of the amorphous phase in the compositetungsten oxide fine particles is 50% or less, as long as the thicknessof the amorphous layer is 10% or less of the particle size.

Meanwhile, when the composite tungsten oxide fine particles aredispersed in a matrix of a solid medium such as a resin constituting thenear-infrared shielding material fine particle dispersion body, and whenthe value obtained by subtracting the crystallite size from the averageparticle size of the dispersed composite tungsten oxide fine particlesis 20% or less of the average particle size, it can be said that thecomposite tungsten oxide fine particles are single crystals in which thevolume ratio of the amorphous phase is 50% or less.

As described above, it is preferable to appropriately adjust a synthesisstep, a pulverization step and a dispersion step of the compositetungsten oxide fine particles in accordance with the productionequipment, so that the value obtained by subtracting the crystallitesize from the average particle size of the composite tungsten oxide fineparticles dispersed in the composite tungsten oxide fine particledispersion body is 20% or less of the value of the average particlesize.

Further, the surface of the fine particles constituting the infraredshielding material of the present invention is coated with an oxidecontaining at least one kind of Si, Ti, Zr and Al. This is preferablefrom a viewpoint of improving the weather resistance of the infraredshielding material.

Further, the near-infrared shielding material fine particle dispersionbody containing the composite tungsten oxide fine particles of thepresent invention absorbs light in the near-infrared region,particularly around the wavelength of 1000 nm, and therefore atransmission color tone thereof is from blue to green in many cases. Thedispersed particle size of the near-infrared shielding material fineparticles can be selected depending on the purpose of use thereof.First, when used for applications for maintaining transparency, thenear-infrared shielding material fine particles preferably have thedispersed particle size of 800 nm or less. This is because particleswith a dispersed particle size of smaller than 800 nm do not completelyshield light by scattering, and it is possible to maintain visibility inthe visible light region and simultaneously maintain transparencyefficiently. Particularly, when emphasis is place on the transparency inthe visible light region, it is preferable to further considerscattering by particles.

The dispersed particle size of the above-described near-infraredshielding material fine particles is a concept including the size of theaggregate of the composite tungsten oxide fine particles, and is aconcept different from the particle size of the near-infrared shieldingmaterial fine particles of the present invention as described above.

When emphasis is placed on reduction of scattering by this particle, thedispersed particle size is preferably 200 nm or less, more preferably 10nm or more and 200 nm or less, further preferably 10 nm or more and 100nm or less. The reason is as follows. When the dispersed particle sizeis small, the scattering of light in the visible light region of awavelength range of 400 nm to 780 nm due to geometric scattering or Miescattering is reduced, and as a result, it is possible to avoid asituation in which an infrared shielding film becomes like a frostedglass and clear transparency cannot be obtained. Namely, when thedispersed particle size becomes 200 nm or less, the above geometricscattering or Mie scattering is reduced and a region becomes a Rayleighscattering region. In the Rayleigh scattering region, the scatteredlight is proportional to the sixth power of the dispersed particle size,and therefore the scattering is reduced with a decrease of the dispersedparticle size and the transparency is improved. Further, when thedispersed particle size becomes 100 nm or less, the scattered light isextremely reduced, which is preferable. From a viewpoint of avoidingscattering of light, it is preferable that the dispersed particle sizeis small, and when the dispersed particle size is 10 nm or more,industrial production is easy.

By setting the dispersed particle size to 800 nm or less, the haze valueof the near-infrared shielding material fine particle dispersion body inwhich the near-infrared shielding material fine particles are dispersedin a medium, can be set to 10% or less with a visible lighttransmittance of 85% or less. Particularly, by setting the dispersedparticle size to 100 nm or less, the haze can be reduced to 1% or less.

It is necessary to examine the light scattering of the near-infraredshielding material fine particle dispersion body, by the dispersedparticle size, in consideration of the aggregate of the near-infraredshielding material fine particles.

It is also found that a near-infrared shielding film produced bydispersing the fine particles in an appropriate medium or on the surfaceof the medium, absorbs the sunlight, particularly the light in thenear-infrared region more efficiently and at the same time transmits thelight in the visible light region even without using the interferenceeffect of light, compared to a film produced by a dry method like avacuum deposition method such as a sputtering method, a vapor depositionmethod, an ion plating method and a chemical vapor deposition method(CVD method), or a film prepared by CVD method or spray method.

2. Method for Producing the Near-Infrared Shielding Material FineParticles

The composite tungsten oxide fine particles expressed by the generalformula MxWyOz of the present invention, can be produced by a solidphase reaction method of applying heat treatment to a tungsten compoundas a starting material for the tungsten oxide fine particles in areducing gas atmosphere, a mixed gas atmosphere of a reducing gas and aninert gas, or an inert gas atmosphere. After passing through the heattreatment, the composite tungsten oxide fine particles obtained by beingmade finer by pulverization treatment or the like so as to have apredetermined particle size, have sufficient near-infrared absorbingpower and have preferable properties as near-infrared shielding fineparticles.

As a starting material for obtaining the composite tungsten oxide fineparticles expressed by the above general formula MxWyOz of the presentinvention, it is possible to use a mixed powder at a ratio of0.20≤x/y≤0.37, the mixed powder being one or more powder selected fromtungsten trioxide powder, tungsten dioxide powder, or a hydrate oftungsten oxide, or tungsten hexachloride powder, or ammonium tungstatepowder, or a tungsten oxide hydrate powder obtained by dissolvingtungsten hexachloride in alcohol and drying the mixture, or a tungstenoxide hydrate powder obtained by dissolving tungsten hexachloride inalcohol, making it precipitated by adding water and drying, or atungsten compound powder obtained by drying an aqueous ammoniumtungstate solution, or a metal tungsten powder, and a powder of a simplesubstance or a compound containing M element.

Further, when the tungsten compound as the starting material forobtaining the composite tungsten oxide fine particles is a solution or adispersion liquid, each element can easily be uniformly mixed.

From this viewpoint, it is further preferable that the starting materialof the composite tungsten oxide fine particles is a powder obtained bymixing an alcohol solution of tungsten hexachloride, an ammoniumtungstate solution, and a solution of a compound containing the Melement, and then drying the mixture.

From a similar viewpoint, it is also preferable that the startingmaterial of the composite tungsten oxide fine particles is a powderobtained by mixing a dispersion liquid prepared by dissolving tungstenhexachloride in alcohol and then adding water to form a precipitate, andpowder of simple substance or compound containing M element or asolution of the compound containing the M element, and then drying themixture.

Examples of the compound containing the M element include a tungstate, achloride salt, a nitrate, a sulfate, an oxalate, an oxide, a carbonateand a hydroxide of the M element. However, the compound is not limitedthereto and a compound in a solution state may be acceptable. Further,when the composite tungsten oxide fine particles are producedindustrially, hazardous gases and the like are not generated at thestage of the heat treatment or the like, by using tungsten oxide hydratepowder or tungsten trioxide and carbonate or hydroxide of M element,which is a preferable production method.

Here, explanation will be given for heat treatment conditions for thecomposite tungsten oxide fine particles in the reducing atmosphere or inthe mixed gas atmosphere of the reducing gas and the inert gas.

First, the starting material is heat-treated in the reducing gasatmosphere or in the mixed gas atmosphere of the reducing gas and theinert gas. This heat treatment temperature is preferably higher than atemperature at which the composite tungsten oxide fine particles arecrystallized. Specifically, 500° C. or more and 1000° C. or less ispreferable, and 500° C. or more and 800° C. or less is more preferable.If desired, heat treatment may be performed at 500° C. to 1200° C. inthe inert gas atmosphere.

Further, the reducing gas is not particularly limited, but is preferablyH₂. Further, when H₂ is used as the reducing gas, its concentration isnot particularly limited as long as it is appropriately selectedaccording to a firing temperature and an amount of the startingmaterial. For example, the concentration is 20 vol % or less, preferably10 vol % or less, more preferably 7 vol % or less. This is because whenthe concentration of the reducing gas is 20 vol % or less, it ispossible to avoid the generation of WO₂ not having a solar radiationshielding function by rapid reduction.

By this heat treatment, 2.2≤z/y≤3.0 is satisfied in the compositetungsten oxide.

Meanwhile, the method for producing the composite tungsten oxide is notlimited to the solid phase reaction method. By setting an appropriateproducing condition, the composite tungsten oxide can also be producedby a thermal plasma method. Examples of the producing conditions to beappropriately set, include: a supply rate at the time of supplying theraw material into thermal plasma; a flow rate of a carrier gas used forsupplying the raw material; a flow rate of a plasma gas for holding aplasma region; and a flow rate of a sheath gas flowing just outside theplasma region etc.

The heat treatment step of obtaining the composite tungsten oxide or thecomposite tungsten oxide particles described above, may be referred toas a first step of the present invention in some cases.

It is preferable to coat the surface of the near-infrared shieldingmaterial fine particles obtained in the above-described step, with anoxide containing one or more kinds of metals selected from Si, Ti, Zrand Al, from a viewpoint of improving the weather resistance. Thecoating method is not particularly limited, but it is possible to coatthe surface of the near-infrared shielding material fine particles byadding the metal alkoxide into a solution in which the near-infraredshielding material fine particles are dispersed.

A bulk body or the particles of the composite tungsten oxide may be madefiner through the near-infrared shielding material fine particledispersion liquid described later. In order to obtain the compositetungsten oxide fine particles from the near-infrared shielding materialfine particle dispersion liquid, a solvent may be removed by a knownmethod.

Further, as for forming the composite tungsten oxide bulk body andparticles into finer particles, a dry process using a jet mill or thelike is possible for obtaining the finer particles. However, as a matterof course, even in a case of the dry process for obtaining the finerparticles, pulverization conditions (conditions for forming particlesinto finer particles) are set for the particles to have the particlesize, the crystallite size, and a-axis length and c-axis length as thelattice constants of the obtained composite tungsten oxide. For example,if the jet mill is used, it is sufficient to select the jet mill whichhas an air flow rate and a treatment time as appropriate pulverizationconditions.

The step of making the composite tungsten oxide or the compositetungsten oxide particles finer to obtain the near-infrared shieldingmaterial fine particles of the present invention described above, isreferred to as a second step of the present invention in some cases.

3. Near-Infrared Shielding Material Fine Particle Dispersion Liquid

The above-described composite tungsten oxide fine particles mixed anddispersed in an appropriate solvent is the near-infrared shieldingmaterial fine particle dispersion liquid of the present invention. Thesolvent is not particularly limited, and may be appropriately selectedaccording to coating and kneading conditions, a coating and kneadingenvironment, and further a binder when an inorganic binder or a resinbinder is contained. For example, it is possible to use water, variousorganic solvents like alcohols such as ethanol, propanol, butanol,isopropyl alcohol, isobutyl alcohol and diacetone alcohol, ethers suchas methyl ether, ethyl ether, propyl ether, esters, ketones such asacetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, isobutylketone, and aromatic hydrocarbons such as toluene.

Further, if necessary, acid or alkali may be added to adjust pH of thedispersion liquid.

Further, as the solvent, monomers or oligomers of resin may be used.

On the other hand, in order to further improve a dispersion stability ofthe fine particles in the dispersion liquid, it is of course alsopossible to add various dispersants, surfactants, coupling agents andthe like.

In the infrared shielding material fine particle dispersion liquid, when80 parts by weight or more of the solvent is contained based on 100parts by weight of the near-infrared shielding material fine particles,it is easy to ensure preservability as a dispersion liquid, and it ispossible to secure the workability at the time of preparing thenear-infrared shielding material fine particle dispersion bodythereafter.

The method for dispersing the composite tungsten oxide fine particles inthe solvent is a method for uniformly dispersing the fine particles inthe dispersion liquid, and the method is not particularly limited,provided that the particle size of the composite tungsten oxide fineparticles can be adjusted to 100 nm or less, preferably 10 nm or moreand 100 nm or less, more preferably 10 nm or more and 80 nm or less,further preferably 10 nm or more and 60 nm or less, most preferably 10nm or more and 40 nm or less, while securing the range of 7.3850 Å ormore and 7.4186 Å or less on the a-axis and 7.5600 Å or more and 7.6240Å or less on the c-axis in the crystal structure of the compositetungsten oxide fine particles. For example, a bead mill, a ball mill, asand mill, a paint shaker, an ultrasonic homogenizer, and the like canbe used.

By means of a mechanical dispersion treatment step using theseinstruments, the process of forming particles into finer particles isprogressed due to collision between the composite tungsten oxideparticles simultaneously with dispersion of the composite tungsten oxidefine particles in the solvent, strain and deformation are imparted tothe hexagonal crystal structure contained in the composite tungstenoxide particles, thereby changing an overlapping state of the electronorbitals in the atoms constituting the crystallite structure, and theincrease of a free electron amount is accelerated.

The process of forming the composite tungsten oxide particles into finerparticles and fluctuation of a-axis length and c-axis length as thelattice constants in the hexagonal crystal structure, are differentdepending on device constants of a pulverizer. Accordingly, it isimportant to perform experimental pulverization beforehand, anddetermine a pulverizer and pulverizing conditions for the compositetungsten oxide fine particles to have a predetermined particle size,crystallite size, a-axis length and c-axis length as the latticeconstants.

Particularly, depending on the conditions at the time of forming thecomposite tungsten oxide particles into finer particles, the latticeconstant of the composite tungsten oxide fine particles does not satisfy7.3850 Å or more and 7.4186 Å or less on the a-axis, and 7.5600 Å ormore and 7.6240 Å or less on the c-axis in some cases. Therefore, as acondition for forming the composite tungsten oxide particles into finerparticles, it is important to set the conditions to ensure that thelattice constant of the composite tungsten oxide fine particles obtainedby forming the particles into finer particles, is 7.3850 Å or more and7.4186 Å or less on the a-axis and 7.5600 Å or more and 7.6240 Å or lesson the c-axis.

The composite tungsten oxide fine particles of the present inventionexhibit a sufficient near-infrared shielding function by satisfying theabove-described lattice constant. Therefore it is important to payattention to setting conditions when forming particles into finerparticles.

Even when the infrared shielding material fine particles are formed intofiner particles through the near-infrared shielding material fineparticle dispersion liquid, and then the solvent is removed to obtainthe near-infrared shielding material fine particles, it is a matter ofcourse that the pulverizing conditions (conditions for forming finerparticles) are set, for the particles to have a particle size, acrystallite size, and a-axis length and c-axis length as the latticeconstants.

A state of the near-infrared shielding material fine particle dispersionliquid of the present invention can be confirmed by measuring adispersion state of the composite tungsten oxide fine particles when thetungsten oxide fine particles are dispersed in the solvent. For example,the composite tungsten oxide fine particles of the present invention canbe confirmed by sampling a sample from a liquid existing as fineparticles and an aggregated state of the fine particles in the solvent,and measuring the sample with various commercially available particlesize distribution meters. As a particle size distribution meter, forexample, a known measuring device such as ELS-8000 manufactured byOtsuka Electronics Co., Ltd. based on the principle of dynamic lightscattering method can be used.

Further, the measurement of the crystal structure and the latticeconstant of the composite tungsten oxide fine particles is performed asfollows. For the composite tungsten oxide fine particles obtained byremoving the solvent of the near-infrared shielding dispersion liquid,the crystal structure contained in the fine particles is specified by anX-ray diffraction method, and by using the Rietveld method, a-axislength and c-axis length are calculated as the lattice constants.

From the viewpoint of optical properties, the dispersed particle size ofthe composite tungsten oxide fine particles is preferably sufficientlyfine from 800 nm or less, preferably 200 nm or less, more preferably 100nm or less. Further, it is preferable that the composite tungsten oxidefine particles are uniformly dispersed.

This is because when the dispersed particle size of the compositetungsten oxide fine particles is 800 nm or less, preferably 200 nm orless, more preferably 10 nm or more and 200 nm or less, furtherpreferably 10 nm or more and 100 nm or less, it is possible to avoid asituation in which the produced near-infrared shielding film or moldedbody (plate, sheet, etc.) becomes monotonously gray-colored one withreduced transmittance.

The term “dispersed particle size” of the present invention is a conceptmeaning the particle size of the single particles of the compositetungsten oxide fine particles or the aggregated particles in which thecomposite tungsten oxide fine particles are aggregated which aredispersed in the near-infrared shielding material fine particledispersion liquid. The dispersed particle size can be measured withvarious commercially available particle size distribution meters, andcan be measured, for example by sampling the sample of the compositetungsten oxide fine particle dispersion liquid, and measuring the sampleusing a particle size measuring device based on the dynamic lightscattering method (ELS-8000 manufactured by Otsuka Electronics Co.,Ltd.).

On the other hand, in the near-infrared shielding material fine particledispersion liquid, the composite tungsten oxide fine particles areaggregated to form coarse aggregates, and when there are many coarseparticles, the coarse particles become light scattering sources. As aresult, when the near-infrared shielding material fine particledispersion liquid becomes a near-infrared shielding film or a moldedbody, the cloudiness (haze) is increased, which may cause reduction ofthe visible light transmittance. Accordingly, it is preferable to avoidformation of coarse particles of the composite tungsten oxide fineparticles.

4. Near-Infrared Shielding Material Fine Particle Dispersion Body

The near-infrared shielding material fine particle dispersion body ofthe present invention is obtained by dispersing the above-describedcomposite tungsten oxide fine particles in an appropriate solid medium.

The near-infrared shielding material fine particle dispersion body ofthe present invention has an advantage that it can be applied to asubstrate material having a low heat resistance temperature such as aresin material, and it is inexpensive without requiring a large-sizedapparatus at the time of forming, because a dispersed state ismaintained in a solid medium such as a resin after the compositetungsten oxide fine particles are mechanically pulverized underpredetermined conditions.

The step of dispersing the near-infrared shielding material fineparticles of the present invention in the solid medium to obtain thenear-infrared shielding material fine particle dispersion body describedabove, is referred to as a third step of the present invention in somecases. Details of the third step will be described later.

Further, the near-infrared shielding material of the present inventionis a conductive material, and therefore when used as a continuous film,there is a danger that it will interfere with radio waves of mobilephones, etc., by absorbing and reflecting the waves. However, when thenear-infrared shielding material is dispersed in the matrix of the solidmedium as fine particles, each particle is dispersed in an isolatedstate, and therefore the near-infrared shielding material hasversatility because it exhibits radio wave transparency.

There is sometimes a difference between the average particle size of thecomposite tungsten oxide fine particles dispersed in the matrix of thesolid medium of the near-infrared shielding material fine particledispersion body, and the dispersed particle size of the compositetungsten oxide fine particles dispersed in the near-infrared shieldingmaterial fine particle dispersion liquid used for forming thenear-infrared shielding material fine particle dispersion body and thedispersion liquid for forming a near-infrared shielding body. This isbecause the aggregation of the composite tungsten oxide fine particlesaggregated in the dispersion liquid is dissolved when the near-infraredshielding material fine particle dispersion body is obtained from thenear-infrared shielding material fine particle dispersion liquid and thedispersion liquid for forming the near-infrared shielding body.

Further, as the solid medium of the near-infrared shielding materialfine particle dispersion body, various resins and glasses can be used.When the solid medium is contained in an amount of 80 parts by weight ormore based on 100 parts by weight of the near-infrared shieldingmaterial fine particles, the near-infrared shielding material fineparticle dispersion body can be preferably formed.

5. Near-Infrared Shielding Effect of the Near-Infrared ShieldingMaterial Fine Particle Dispersion Body

The near-infrared shielding material fine particle dispersion body inwhich the near-infrared shielding material fine particles of the presentinvention are used, has a light transmittance with a maximum value in awavelength range of 350 nm to 600 nm, and a minimum value in awavelength range of 800 nm to 2100 nm, and when the difference betweenthe maximum value (%) and the minimum value (%) is expressed as apercentage, it is possible to obtain the near-infrared shieldingmaterial fine particle dispersion body having especially an excellentoptical property that the maximum value (%)−the minimum value (%)≥69(points), namely, the difference between the maximum value and theminimum value is 69 points or more in percentage. When the differencebetween the maximum value and the minimum value of the transmittance inthe near-infrared shielding material fine particle dispersion body is aslarge as 69 points or more, this means that the near-infrared shieldingproperty of the dispersion body is excellent.

6. Near-Infrared Shielding Body

In the near-infrared shielding body of the present invention, thenear-infrared shielding material fine particle dispersion body of thepresent invention is formed into any one selected from a plate shape, afilm shape, and a thin film shape.

The step of forming the near-infrared shielding material fine particledispersion body of the present invention into the near-infraredshielding body described above, is referred to as a fourth step of thepresent invention in some cases. Note that the fourth step includesforming the near-infrared shielding body on the substrate surface.

7. Method for Producing a Near-Infrared Shielding Material Fine ParticleDispersion Body and a Near-Infrared Shielding Body

As a method for producing a near-infrared shielding material fineparticle dispersion body and a method for forming the near-infraredshielding material fine particle dispersion body into any one selectedfrom a plate shape, a film shape, and a thin film shape, to obtain anear-infrared shielding body, (a) Method for dispersing fine particlesin a solid medium to form the near-infrared shielding body on thesubstrate surface, and (b) Method for dispersing fine particles in asolid medium to form the near-infrared shielding body, will bedescribed.

(a) Method for Dispersing Fine Particles in a Solid Medium to Form theNear-Infrared Shielding Body on the Substrate Surface

The resin constituting the solid medium is added to the obtainednear-infrared shielding material fine particle dispersion liquid toobtain a dispersion liquid for forming a near-infrared shielding body,and thereafter a substrate surface is coated with the dispersion liquidfor forming the near-infrared shielding body, and a solvent isevaporated and the resin is cured by a predetermined method. Thereby, itis possible to obtain the infrared shielding body in which the nearinfrared shielding material fine particle dispersion body is formed onthe substrate surface.

Further, as the solvent of the near-infrared shielding material fineparticle dispersion liquid of the present invention, a monomer of theresin to be a solid medium by curing may be used. When a resin monomeris used as a solvent, a coating method is not particularly limited aslong as the substrate surface can be uniformly coated with the nearinfrared shielding material fine particle dispersion body. For example,a bar coating method, a gravure coating method, a spray coating method,a dip coating method, and the like, can be used. Further, in a case ofthe near-infrared shielding material fine particle dispersion body inwhich the near infrared shielding material fine particles are directlydispersed in a binder resin, there is no need to evaporate the solventafter coating the substrate surface, which is environmentally andindustrially preferable.

As the above-described solid medium, for example, UV curing resin,thermosetting resin, electron beam curing resin, room temperature curingresin, thermoplastic resin, etc., can be selected as the resin accordingto the purpose of use. Specifically, it is possible to use polyethyleneresin, polyvinyl chloride resin, polyvinylidene chloride resin,polyvinyl alcohol resin, polystyrene resin, polypropylene resin,ethylene vinyl acetate copolymer, polyester resin, polyethyleneterephthalate resin, fluororesin, polycarbonate resin, acrylic resin,and polyvinyl butyral resin. These resins may be used alone or incombination.

Further, as the solid medium, it is also possible to use a binder inwhich a metal alkoxide is used. As the metal alkoxide, alkoxides such asSi, Ti, Al, Zr are representative. The binder in which these metalalkoxides are used, is capable of forming an oxide film byhydrolysis/polycondensation by heating or the like.

Meanwhile, as the substrate of the above-described near-infraredshielding body, it may be a film or a board if desired, and its shape isnot limited. As the material of the transparent substrate, PET, acrylic,urethane, polycarbonate, polyethylene, ethylene vinyl acetate copolymer,vinyl chloride, fluorine resin, etc., can be used according to variouspurposes. Further, glass can be used except for resin.

(b) Method for Dispersing Fine Particles in the Solid Medium to Form theNear-Infrared Shielding Body.

As another method for using the near-infrared shielding material of thepresent invention as fine particles, after mechanical pulverizationunder predetermined conditions, the near-infrared shielding materialfine particles may be dispersed in a medium which is a substrate.

In order to disperse the fine particles in the medium, the fineparticles may be permeated from the surface of the medium, but it isalso acceptable that the medium such as a polycarbonate resin is meltedby raising its temperature to not lower than a melting temperature ofthe medium, then the fine particles and the medium are mixed, to therebyobtain the near-infrared shielding material fine particle dispersionbody. The near-infrared shielding material fine particle dispersion bodythus obtained is formed into a film or a board shape, to obtain thenear-infrared shielding body.

For example, as a method for dispersing the near-infrared shieldingmaterial fine particles in PET resin, first, PET resin and thenear-infrared shielding material fine particle dispersion liquid aftermechanical pulverization under predetermined conditions are mixed, andafter a dispersion solvent is evaporated, the mixture is heated to about300° C. which is a melting temperature of the PET resin, and by melting,mixing and cooling the PET resin, it is possible to prepare thenear-infrared shielding body in which the near infrared shieldingmaterial fine particles are dispersed.

8. Near-Infrared Shielding Laminated Structure and a Method forProducing the Same

In the near-infrared shielding laminated structure of the presentinvention, the near-infrared shielding material fine particle dispersionbody of the present invention is present between two or more laminatedplates selected from a plate glass, a plastic plate, and a plastic platecontaining fine particles having a solar radiation shielding function.

The heat ray shielding laminated transparent substrate in which the heatray shielding film of the present invention is used, has various forms.

For example, the heat ray shielding laminated inorganic glass in whichinorganic glass is used, which is a transparent substrate, can beobtained by integrally laminating a plurality of opposed inorganicglasses with a heat ray shielding film sandwiched between them, by aknown method. The obtained heat ray shielding laminated inorganic glasscan be mainly used as a front inorganic glass of an automobile or awindow of a building.

The step of sandwiching the near-infrared shielding body of the presentinvention between two or more opposed transparent substrates, isreferred to as a fifth step of the present invention in some cases.

The heat ray shielding laminated transparent substrate can be obtainedby using transparent resin as the transparent substrate, and bysandwiching the heat ray shielding film so as to be present between twoor more laminated plates selected from a plate glass, a plastic plate,and a plastic plate containing fine particles having a solar radiationshielding function, in the same manner as in a case of using theabove-described inorganic glass. The purpose of use is the same as thatof the heat ray shielding laminated inorganic glass.

Further, it is of course possible to use the heat ray shielding film asa simple body, or possible to use the heat ray shielding film by placingit on one side or both sides of the transparent substrate such asinorganic glass or transparent resin.

9. Conclusion

The near-infrared shielding material fine particle dispersion body, thenear-infrared shielding body and the near-infrared shielding laminatedstructure of the present invention, exhibit excellent optical propertiessuch as shielding the sunlight, particularly the light in thenear-infrared region more efficiently and at the same time maintaining ahigh transmittance in the visible light region, compared to theconventional near-infrared shielding material fine particle dispersionbody, near-infrared ray shielding body and near-infrared shieldinglaminated structure.

Then, the near-infrared shielding film formed on the surface of themedium using the near-infrared shielding material fine particledispersion body of the present invention in which the near-infraredshielding material fine particles are dispersed in the solid medium,exhibits excellent optical properties such as shielding the sunlight,particularly the light in the near-infrared region more efficiently, andat the same time maintaining a high transmittance in the visible lightregion, compared to a film produced by a dry method like a vacuum filmformation method such as a sputtering method, a vapor deposition method,an ion plating method, and a chemical vapor deposition (CVD method), ora layer produced by a CVD method or a spray method.

Further, the near-infrared shielding body and the near-infraredshielding laminated structure of the present invention, can be producedat a low cost without using a large-scale apparatus such as a vacuumapparatus, and are industrially useful.

EXAMPLES

Hereinafter, the present invention will be described in more detail byway of examples, but the present invention is not limited thereto.

Further, for the measurement of the crystal structure, the latticeconstant and the crystallite size of the composite tungsten oxide fineparticles of the present invention, the composite tungsten oxide fineparticles obtained by removing the solvent from the dispersion liquidfor forming the near-infrared shielding body was used. Then, an X-raydiffraction pattern of the composite tungsten oxide fine particles wasmeasured by a powder X-ray diffraction method (θ-2θ method) using apowder X-ray diffractometer (X'Pert-PRO/MPD manufactured by SpectrisCorporation PANalytical). From the obtained X-ray diffraction pattern,the crystal structure contained in the fine particle was specified, andfurther, the lattice constant and the crystallite size were calculatedusing the Rietveld method.

Example 1

7.43 kg of cesium carbonate (Cs₂CO₃) was dissolved in 6.70 kg of waterto obtain a solution. The solution was added to 34.57 kg of tungsticacid (H₂WO₄) and sufficiently stirred and mixed, and thereafter driedwhile stirring (the molar ratio between W and Cs is equivalent to1:0.33). The dried product was heated while supplying 5 vol % of H₂ gasusing N₂ gas as a carrier, and fired at a temperature of 800° C. for 5.5hours, and thereafter, the supply gas was switched to N₂ gas only, andthe temperature was lowered to room temperature to obtain Cs tungstenoxide particles a.

20 mass % of the Cs tungsten oxide particle a, 8 mass % of an acrylicpolymer dispersant (amine value: 48 mg KOH/g, acrylic dispersant havinga decomposition temperature of 250° C.) having a group containing anamine as a functional group (referred to as “dispersant a” hereafter),and 72 mass % of butyl acetate were weighed, and a mixture was chargedin a paint shaker (manufactured by Asada Iron Works Co., Ltd.)containing 0.3 mmϕ ZrO₂ beads, followed by pulverization/dispersiontreatment for 20 hours to prepare a near-infrared shielding materialfine particle dispersion liquid (A-1 solution).

Here, when the dispersed particle size of the Cs tungsten oxide fineparticles a in the near-infrared shielding material fine particledispersion liquid (A-1 solution) was measured with a particle sizemeasuring device (ELS-8000 manufactured by Otsuka Electronics Co., Ltd.)based on a dynamic light scattering method, it was 70 nm. Further, whenthe lattice constant of the Cs tungsten oxide fine particles a afterremoving the solvent from the (A-1 solution) was measured, it was 7.4071Å on the a-axis, and 7.6188 Å on the c-axis. The crystallite size was 24nm.

Further, the visible light transmittance and the near-infrared shieldingproperty were measured as optical properties of the (A-1 solution) usinga spectrophotometer U-4000 manufactured by Hitachi, Ltd. For themeasurement, a dispersion liquid in which the (A-1 solution) was dilutedwith butyl acetate so as to have a visible light transmittance of around70% in a measuring glass cell of a spectrophotometer was used. Further,in this measurement, an incident direction of light of thespectrophotometer was set to be perpendicular to the measurement glasscell. Further, the transmittance of the light was also measured for ablank solution containing only butyl acetate as a solvent in themeasurement glass cell, and this transmittance was used as a baseline ofthe light transmittance.

Here, the visible light transmittance was obtained according to JIS R3106, and the near-infrared shielding property was obtained, with avalue of the difference between the maximum value of the percentage ofthe transmittance in the visible light region and the minimum value ofthe percentage of the transmittance in the near-infrared light region asa point. As a result, the visible light transmittance was 70.0%, and thedifference between the maximum value and the minimum value of thetransmittance was 76.8 points.

Next, the obtained dispersion liquid (A-1 solution) and the UV curableresin were weighed so that the weight ratio was 1:9, and mixed andstirred to prepare a dispersion liquid for forming a near-infraredshielding body (AA-1 solution).

Then, the dispersion liquid (AA-1 solution) for forming thenear-infrared shielding body was applied onto a soda-lime glasssubstrate having a thickness of 3 mm by using a bar coater of Bar-No 16and dried at 70° C. for 1 minute, and irradiated with a high pressuremercury lamp to obtain a near-infrared shielding body A as anear-infrared shielding material fine particle dispersion body ofexample 1.

Here, for the near-infrared shielding body A, the optical propertieswere measured in the same manner as in the above-described near-infraredshielding material fine particle dispersion liquid (A-1 solution). As aresult, the visible light transmittance was 69.7%, and the differencebetween the maximum value and the minimum value of the transmittance was74.1 points. Further, the transmittance for light having wavelengths of550 nm, 1000 nm, and 1500 nm was measured. In addition, a flaked sampleof the near-infrared shielding body A was prepared by cross-sectionalprocessing using FIB processor FB2200 manufactured by HitachiHigh-Technologies Corporation, and when the average particle size of 100Cs tungsten oxide fine particles dispersed in the near-infraredshielding body A was calculated by TEM observation using a transmissionelectron microscope HF-2200 manufactured by Hitachi High-TechnologiesCorporation, it was found to be 25 nm.

Hereinafter, the same measurement was performed also in example 2 to 17and comparative example 1 to 9. Then, the results of example 1 to 17 areshown in Table 1, and the results of comparative example 1 to 9 areshown in Table 2.

Example 2

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.31 in example 1, infrared shielding material fineparticle dispersion liquid (A-2 solution), Cs tungsten oxide fineparticles b, and near-infrared shielding body B of example 2 wereobtained.

The dispersed particle size of the Cs tungsten oxide fine particles b inthe near-infrared shielding material fine particle dispersion liquid(A-2 solution) was 70 nm. Then, the lattice constant of the Cs tungstenoxide fine particles b was 7.4100 Å on the a-axis and 7.6138 Å on thec-axis. The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body B,the visible light transmittance was 69.8%, and the difference betweenthe maximum value and the minimum value of the transmittance was 73.0points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body B wasfound to be 25 nm. The results are shown in Table 1.

Example 3

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.35 in example 1, infrared shielding material fineparticle dispersion liquid (A-3 solution), Cs tungsten oxide fineparticles c and near-infrared shielding body C of example 3 wereobtained.

The dispersed particle size of the Cs tungsten oxide fine particles c inthe near-infrared shielding material fine particle dispersion liquid(A-3 solution) was 70 nm. The lattice constant of the Cs tungsten oxidefine particles c was 7.4065 Å on the a-axis and 7.6203 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body C,the visible light transmittance was 69.8%, and the difference betweenthe maximum value and the minimum value of the transmittance was 73.6points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shield C was foundto be 24 nm. The results are shown in Table 1.

Example 4

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.37 in example 1, dispersion liquid (A-4 solution)for forming the infrared shielding body, Cs tungsten oxide fineparticles d and near-infrared shielding body D of example 4 wereobtained.

The dispersed particle size of the Cs tungsten oxide fine particles d inthe infrared shielding material fine particle dispersion liquid (A-4solution) was 70 nm. The lattice constant of the Cs tungsten oxide fineparticles d was 7.4066 Å on the a-axis and 7.6204 Å on the c-axis. Thecrystallite size was 24 nm. Then, as a result of measuring the visiblelight transmittance and the near-infrared shielding property of thenear-infrared shielding body D, the visible light transmittance was69.8%, and the difference between the maximum value and the minimumvalue of the transmittance was 73.6 points. By TEM observation, theaverage particle size of the Cs tungsten oxide fine particles dispersedin the near-infrared shielding body D was found to be 25 nm. The resultsare shown in Table 1.

Example 5

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.33, the infrared shielding material fine particle dispersion liquid(A-5 solution), Cs tungsten oxide fine particles e, and near-infraredshielding body E of example 5 were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles e inthe near-infrared shielding material fine particle dispersion liquid(A-5 solution) was 70 nm. The lattice constant of the Cs tungsten oxidefine particles e was 7.4065 Å on the a-axis and 7.6193 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding E, thevisible light transmittance was 71.7%, and the difference between themaximum value and the minimum value of the transmittance was 70.0points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body E wasfound to be 25 nm. The results are shown in Table 1.

Comparative Example 1

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.11 in example 1, infrared shielding material fineparticle dispersion liquid (A-6 solution), Cs tungsten oxide fineparticles f and near-infrared shielding body F of comparative example 1were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles f inthe near-infrared shielding material fine particle dispersion liquid(A-6 solution) was 70 nm. The lattice constant of the Cs tungsten oxidefine particles f was 7.4189 Å on the a-axis and 7.5825 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body F,the visible light transmittance was 69.3%, and the difference betweenthe maximum value and the minimum value of the transmittance was 63.4points, which was less than 69 points. By TEM observation, the averageparticle size of the Cs tungsten oxide fine particles dispersed in thenear-infrared shield F was found to be 24 nm. The results are shown inTable 2.

Comparative Example 2

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.15 in example 1, infrared shielding material fineparticle dispersion liquid (A-7 solution), Cs tungsten oxide fineparticles g, and near-infrared shielding body G of comparative example 2were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles g inthe near-infrared shielding material fine particle dispersion liquid(A-7 liquid) was 70 nm. The lattice constant of the Cs tungsten oxidefine particles g was 7.4188 Å on the a-axis and 7.5826 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body G,the visible light transmittance was 69.4%, and the difference betweenthe maximum value and the minimum value of the transmittance was 66.1points, which was less than 69 points. By TEM observation, the averageparticle size of the Cs tungsten oxide fine particles dispersed in thenear-infrared shielding body G was found to be 25 nm. The results areshown in Table 2.

Comparative Example 3

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.39 in example 1, infrared shielding material fineparticle dispersion liquid (A-8 solution), Cs tungsten oxide fineparticles h and near-infrared shielding body H of comparative example 2were obtained.

The dispersed particle size of Cs tungsten oxide fine particles g in thenear-infrared shielding material fine particle dispersion liquid (A-8solution) was 70 nm. The lattice constant of the Cs tungsten oxide fineparticles g was 7.4025 Å on the a-axis and 7.6250 Å on the c-axis. Thecrystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body G,the visible light transmittance was 69.6%, and the difference betweenthe maximum value and the minimum value of the transmittance was 67.2points, which was less than 69 points. By TEM observation, the averageparticle size of the Cs tungsten oxide fine particles dispersed in thenear-infrared shielding body H was found to be 25 nm. The results areshown in Table 2.

Example 6

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.21 in example 1, infrared shielding material fine particledispersion liquid (A-9 solution), Cs tungsten oxide fine particles i andnear-infrared shielding body I of example 6 were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles i inthe near-infrared shielding material fine particle dispersion liquid(A-9 solution) was 70 nm. The lattice constant of the Cs tungsten oxidefine particles i were 7.4186 Å on the a-axis and 7.5825 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared ray shield E, thevisible light transmittance was 69.4%, and the difference between themaximum value and the minimum value of the transmittance was 69.3points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body I wasfound to be 24 nm. The results are shown in Table 1.

Example 7

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.23 in example 1, infrared shielding material fine particledispersion liquid (A-10 solution), Cs tungsten oxide fine particles j,and near-infrared shielding body J of example 7 were obtained.

The dispersed particle size of Cs tungsten oxide fine particles j in thenear-infrared shielding material fine particle dispersion liquid (A-10solution) was 70 nm. The lattice constant of the Cs tungsten oxide fineparticles j was 7.4184 Å on the a-axis and 7.5823 Å on the c-axis. Thecrystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body J,the visible light transmittance was 69.8%, and the difference betweenthe maximum value and the minimum value of the transmittance was 70.5points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body J wasfound to be 25 nm. The results are shown in Table 1.

Example 8

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.25 in example 1, infrared shielding material fine particledispersion liquid (A-11 solution), Cs tungsten oxide fine particles k,and near-infrared shielding body K of example 8 were obtained.

The dispersed particle size of Cs tungsten oxide fine particles k in thenear-infrared shielding material fine particle dispersion liquid (A-11solution) was 70 nm. The lattice constant of the Cs tungsten oxide fineparticles k was 7.4165 Å on the a-axis and 7.5897 Å on the c-axis. Thecrystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body K,the visible light transmittance was 69.8%, and the difference betweenthe maximum value and the minimum value of the transmittance was 73.2points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body K wasfound to be 24 nm. The results are shown in Table 1.

Example 9

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.27 in example 1, infrared shielding material fine particledispersion liquid (A-12 solution), Cs tungsten oxide fine particles 1and near-infrared shielding body L of example 9 were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles 1 inthe near-infrared shielding material fine particle dispersion liquid(A-12 solution) was 70 nm. The lattice constant of the Cs tungsten oxideparticle 1 was 7.4159 Å on the a-axis and 7.5919 Å on the c-axis. Thecrystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body L,the visible light transmittance was 69.5%, and the difference betweenthe maximum value and the minimum value of the transmittance was 72.4points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body L wasfound to be 25 nm. The results are shown in Table 1.

Example 10

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.29 in example 1, infrared shielding material fine particledispersion liquid (A-13 liquid), Cs tungsten oxide fine particles m andnear-infrared shielding body M of example 10 were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles m inthe near-infrared shielding material fine particle dispersion liquid(A-13 solution) was 70 nm. The lattice constant of the Cs tungsten oxidefine particles m was 7.4133 Å on the a-axis and 7.6002 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body M,the visible light transmittance was 69.9%, and the difference betweenthe maximum value and the minimum value of the transmittance was 72.8points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding M wasfound to be 25 nm. The results are shown in Table 1.

Example 11

In the same manner as in example 1 except that predetermined amounts ofan aqueous ammonium metatungstate solution (50 wt % in terms of WO₃) andcesium carbonate were weighed so that the molar ratio of W and Cs was1:0.30 in example 1, infrared shielding material fine particledispersion liquid (A-14 solution), Cs tungsten oxide fine particles n,and near-infrared shielding body N of example 11 were obtained.

The dispersed particle size of the Cs tungsten oxide fine particles n inthe near-infrared shielding material fine particle dispersion liquid(A-14 solution) was 70 nm. The lattice constant of Cs tungsten oxidefine particles n was 7.4118 Å on the a-axis and 7.6082 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body N,the visible light transmittance was 69.7%, and the difference betweenthe maximum value and the minimum value of the transmittance was 72.3points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shield N was foundto be 24 nm. The results are shown in Table 1.

Example 12

In the same manner as in example 1 except that firing was performed at550° C. for 9.0 hours while supplying 50% H₂ gas using N₂ gas as acarrier in example 1, infrared shielding material fine particledispersion liquid (A-15 solution), Cs tungsten oxide fine particle o,and near-infrared shielding body O of example 12 were obtained.

The dispersed particle size of Cs tungsten oxide fine particles o in thenear-infrared shielding material fine particle dispersion liquid (A-15solution) was 70 nm. The lattice constant of the Cs tungsten oxide fineparticles o was 7.4068 Å on the a-axis and 7.6190 Å on the c-axis. Thecrystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body O,the visible light transmittance was 69.9%, and the difference betweenthe maximum value and the minimum value of the transmittance was 74.0points. By TEM observation, the average particle size of the Cs tungstenoxide fine particles dispersed in the near-infrared shielding body O wasfound to be 25 nm. The results are shown in Table 1.

Example 13

5.56 kg of rubidium carbonate (Rb₂CO₃) was dissolved in 6.70 kg of waterto obtain a solution. The solution was added to 36.44 kg of tungsticacid (H₂WO₄) and sufficiently stirred and mixed, and thereafter driedwhile stirring (the molar ratio between W and Rb is equivalent to1:0.33). The dried product was heated while supplying 5 vol % of H₂ gasusing N₂ gas as a carrier, and fired at a temperature of 800° C. for 5.5hours, and thereafter, the supply gas was switched to N₂ gas only, andthe temperature was lowered to room temperature to obtain Rb tungstenoxide particles.

In the same manner as in example 1 except that the obtained Rb tungstenoxide particles were used instead of Cs tungsten oxide particles,infrared shielding material fine particle dispersion liquid (B-1solution), Rb tungsten oxide fine particles a, and near-infraredshielding body B1 of example 13 were obtained.

The dispersed particle size of the Rb tungsten oxide fine particles a inthe near-infrared shielding material fine particle dispersion liquid(B-1 solution) was 70 nm. The lattice constant of the Rb tungsten oxidefine particles a was 7.3898 Å on the a-axis and 7.5633 Å on the c-axis.The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body B1,the visible light transmittance was 69.6%, and the difference betweenthe maximum value and the minimum value of the transmittance was 69.5points. By TEM observation, the average particle size of the Rb tungstenoxide fine particles dispersed in the near-infrared shielding body B1was found to be 25 nm. The results are shown in Table 1.

Example 14

0.709 kg of cesium carbonate (Cs₂CO₃) and 5.03 kg of rubidium carbonate(Rb₂CO₃) were dissolved in 6.70 kg of water to obtain a solution. Thesolution was added to 36.26 kg of tungstic acid (H₂WO₄) and sufficientlystirred and mixed, and thereafter dried while stirring (the molar ratiobetween W and Cs is equivalent to 1:0.03, and the molar ratio between Wand Rb is equivalent to 1:0.30). The dried product was heated whilesupplying 5% H₂ gas using N₂ gas as a carrier, and fired at atemperature of 800° C. for 5.5 hours, and thereafter, the supply gas wasswitched to N₂ gas only, and the temperature was lowered to roomtemperature to obtain CsRb tungsten oxide particles a.

In the same manner as in example 1 except that the obtained CsRbtungsten oxide particles a were used instead of the Cs tungsten oxideparticles, infrared shielding material fine particle dispersion liquid(C-1 solution), CsRb tungsten oxide fine particles a and near-infraredshielding body C1 of example 14 were obtained.

The dispersed particle size of the CsRb tungsten oxide fine particles ain the near-infrared shielding material fine particle dispersion liquid(C-1 solution) was 70 nm. The lattice constant of the CsRb tungstenoxide fine particles a was 7.3925 Å on the a-axis and 7.5730 Å on thec-axis. The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body,the visible light transmittance was 69.7%, and the difference betweenthe maximum value and the minimum value of the transmittance was 70.4points. By TEM observation, the average particle size of the CsRbtungsten oxide fine particles dispersed in the near-infrared shieldingbody C1 was found to be 24 nm. The results are shown in Table 1.

Example 15

4.60 kg of cesium carbonate (Cs₂CO₃) and 2.12 kg of rubidium carbonate(Rb₂CO₃) were dissolved in 6.70 kg of water to obtain a solution. Thesolution was added to 35.28 kg of tungstic acid (H₂WO₄) and sufficientlystirred and mixed, and thereafter dried while stirring (the molar ratiobetween W and Cs is equivalent to 1:0.20, and the molar ratio between Wand Rb is equivalent to 1:0.13). The dried product was heated whilesupplying 5% H₂ gas using N_(z) gas as a carrier, and fired at atemperature of 800° C. for 5.5 hours, and thereafter, the supply gas wasswitched to N₂ gas only, and the temperature was lowered to roomtemperature to obtain CsRb tungsten oxide particles b.

In the same manner as in example 1 except that the obtained CsRbtungsten oxide particles b were used instead of the Cs tungsten oxideparticles, infrared shielding material fine particle dispersion liquid(C-2 solution), CsRb tungsten oxide fine particles b and near-infraredshielding body C2 of example 15 were obtained.

The dispersed particle size of the CsRb tungsten oxide fine particles bin the near-infrared shielding material fine particle dispersion liquid(C-2 solution) was 70 nm. The lattice constant of the CsRb tungstenoxide fine particles b was 7.4026 Å on the a-axis and 7.6035 Å on thec-axis. The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body C2,the visible light transmittance was 69.7%, and the difference betweenthe maximum value and the minimum value of the transmittance was 71.5points. By TEM observation, the average particle size of the CsRbtungsten oxide fine particles dispersed in the near-infrared shieldingbody C2 was found to be 24 nm. The results are shown in Table 1.

Example 16

5.71 kg of cesium carbonate (Cs₂CO₃) and 1.29 kg of rubidium carbonate(Rb₂CO₃) were dissolved in 6.70 kg of water to obtain a solution. Thesolution was added to 35.00 kg of tungstic acid (H₂WO₄) and sufficientlystirred and mixed, and thereafter dried while stirring (the molar ratiobetween W and Cs is equivalent to 1:0.25, and the molar ratio between Wand Rb is equivalent to 1:0.08). The dried product was heated whilesupplying 5% H₂ gas using N₂ gas as a carrier, and fired at atemperature of 800° C. for 5.5 hours, and thereafter, the supply gas wasswitched to N₂ gas only, and the temperature was lowered to roomtemperature to obtain CsRb tungsten oxide particles c.

In the same manner as in example 1 except that the obtained CsRbtungsten oxide particles c were used instead of the Cs tungsten oxideparticles, infrared shielding material fine particle dispersion liquid(C-3 solution), CsRb tungsten oxide fine particles c and near-infraredshielding body C3 of example 16 were obtained.

The dispersed particle size of the CsRb tungsten oxide fine particles cin the near-infrared shielding material fine particle dispersion liquid(C-3 solution) was 70 nm. The lattice constant of the CsRb tungstenoxide fine particles c was 7.4049 Å on the a-axis and 7.6083 Å on thec-axis. The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body,the visible light transmittance was 69.7%, and the difference betweenthe maximum value and the minimum value of the transmittance was 71.5points. By TEM observation, the average particle size of the CsRbtungsten oxide fine particles dispersed in the near-infrared shieldingbody C3 was found to be 25 nm. The results are shown in Table 1.

Example 17

6.79 kg of cesium carbonate (Cs₂CO₃) and 0.481 kg of rubidium carbonate(Rb₂CO₃) were dissolved in 6.70 kg of water to obtain a solution. Thesolution was added to 34.73 kg of tungstic acid (H₂WO₄) and sufficientlystirred and mixed, and thereafter dried while stirring (the molar ratiobetween W and Cs is equivalent to 1:0.30, and the molar ratio between Wand Rb is equivalent to 1:0.03). The dried product was heated whilesupplying 5% H₂ gas using N₂ gas as a carrier, and fired at atemperature of 800° C. for 5.5 hours, and thereafter, the supply gas wasswitched to N₂ gas only, and the temperature was lowered to roomtemperature to obtain CsRb tungsten oxide particles d.

In the same manner as in example 1 except that the obtained CsRbtungsten oxide particles d were used instead of the Cs tungsten oxideparticles, infrared shielding material fine particle dispersion liquid(C-4 solution), CsRb tungsten oxide fine particles d and near-infraredshielding body C4 of example 17 were obtained.

The dispersed particle size of the CsRb tungsten oxide fine particles din the near-infrared shielding material fine particle dispersion liquid(C-4 solution) was 70 nm. The lattice constant of the CsRb tungstenoxide fine particles d was 7.4061 Å on the a-axis and 7.6087 Å on thec-axis. The crystallite size was 24 nm.

Then, as a result of measuring the visible light transmittance and thenear-infrared shielding property of the near-infrared shielding body C4,the visible light transmittance was 69.5%, and the difference betweenthe maximum value and the minimum value of the transmittance was 72.1points. By TEM observation, the average particle size of the CsRbtungsten oxide fine particles dispersed in the near-infrared shieldingbody C4 was found to be 25 nm. The results are shown in Table 1.

Comparative Examples 4 and 5

In the same manner as in example 1 except that predetermined amounts oftungstic acid and cesium carbonate were weighed so that the molar ratioof W and Cs was 1:0.21 (Comparative Example 4), 1:0.23 (ComparativeExample 5), and fired at a temperature of 400° C. for 5.5 hours inexample 1, dispersion liquid (A-16 solution and A-17 solution) forforming the near-infrared shielding body, Cs tungsten oxide fineparticles p and q, and near-infrared shielding bodies P and Q. Thedispersed particle size of the Cs tungsten oxide fine particles p in thenear-infrared shielding material fine particle dispersion liquid (A-16solution) was 70 nm, and the dispersed particle size of Cs tungstenoxide fine particles q in (A-17 solution) was 70 nm. Infrared shieldingmaterial fine particle dispersion liquids (A-16 solution and A-17solution), Cs tungsten oxide fine particles p and q, near-infraredshielding bodies P and Q were evaluated in the same manner as inexample 1. The results are shown in Table 2.

Comparative Example 6

In the same manner as in example 1 except that a rotational speed of thepaint shaker was set to 0.8 times that in example 1 and thepulverization/dispersion treatment was performed for 100 hours for theCs tungsten oxide particles a of example 1, near-infrared shieldingmaterial dispersion liquid (A-18 solution), Cs tungsten oxide fineparticles r, and near-infrared shielding body R were obtained. Thedispersed particle size of the Cs tungsten oxide fine particles r in thenear-infrared shielding material fine particle dispersion liquid (A-18solution) was 50 nm. The near-infrared shielding material fine particledispersion liquid (A-18 solution), the Cs tungsten oxide fine particlesr, and the near-infrared shielding body R were evaluated in the samemanner as in example 1. The results are shown in Table 2.

Comparative Example 7

In the same manner as in example 1 except that the dried product wasfired at a temperature of 440° C. for 5.5 hours while supplying 3 vol %H₂ gas using N₂ gas as a carrier, for the Cs tungsten oxide particles aof example 1, near-infrared shielding material dispersion liquid (A-19solution), Cs tungsten oxide fine particle s, and near-infraredshielding body S of comparative example 7 were obtained. The dispersedparticle size of the Cs tungsten oxide fine particles s in thenear-infrared shielding material fine particle dispersion liquid (A-19solution) was 75 nm. The near-infrared shielding material fine particledispersion liquid (A-19 solution), the Cs tungsten oxide fine particless, and the near-infrared shielding body S were evaluated in the samemanner as in example 1. The results are shown in Table 2.

Comparative Example 8

20 mass % of the Cs tungsten oxide particles a, 8 mass % of thedispersant a, and 72 mass % of butyl acetate of example 1 were weighed,and mixed by vibration of ultrasonic wave for 10 minutes, to obtaininfrared shielding material dispersion liquid (A-20 solution), Cstungsten oxide particles a, and near-infrared shielding body T. Namely,the Cs tungsten oxide particles a contained in the near-infraredshielding material dispersion liquid (A-20 solution) are not pulverized.The dispersed particle size of the Cs tungsten oxide fine particles a inthe near-infrared shielding material dispersion liquid (A-20 solution)was 150 nm. Infrared shielding material fine particle dispersion liquid(A-20 solution), Cs tungsten oxide particles a, and near-infraredshielding body T were evaluated in the same manner as in example 1. Theresults are shown in Table 2.

Comparative Example 9

In the same manner as in example 1 except that the rotational speed ofthe paint shaker was set to 1.15 times that in example 1 and thepulverization/dispersion treatment was performed for 50 hours for the Cstungsten oxide particles a of example 1, near-infrared shieldingmaterial dispersion liquid (A-21 solution), Cs tungsten oxide fineparticles u, and near-infrared shielding body U were obtained. Thedispersed particle size of the Cs tungsten oxide fine particles u in thenear-infrared shielding material fine particle dispersion liquid (A-21solution) was 110 nm. Near-infrared shielding material fine particledispersion liquid (A-21 solution), Cs tungsten oxide fine particles u,and near-infrared shielding body U were evaluated in the same manner asin example 1. The results are shown in Table 2.

CONCLUSION

As is clear from Tables 1 and 2, it is found that the near-infraredshielding body produced using the near-infrared shielding material fineparticle dispersion liquid containing the near-infrared shieldingmaterial fine particles of examples 1 to 17, exhibits excellent opticalproperties such as shielding the sunlight, particularly the light in thenear-infrared region more efficiently and at the same time maintaining ahigh transmittance in the visible light region, compared to thenear-infrared shielding body produced using the near-infrared shieldingmaterial fine particle dispersion liquid containing the near-infraredshielding material fine particles of comparative examples 1 to 9.

Particularly, in all of the near-infrared shielding bodies of examples 1to 17, the difference between the maximum value and the minimum value ofthe light transmittance exceeds 69 points. In contrast, in all of thenear-infrared shielding bodies of comparative examples 1 to 9, thedifference was less than 69 points.

As described above, it is found that the near-infrared shieldingmaterial fine particle dispersion body, the near-infrared shielding bodyand the near-infrared shielding laminated structure produced using themaccording to the present invention, exhibit excellent optical propertiessuch as shielding the sunlight, particularly the light in thenear-infrared region more efficiently and at the same time maintaining ahigh transmittance in the visible light region, compared to theconventional near-infrared shielding material fine particle dispersionbody, near-infrared ray shielding body and near-infrared shieldinglaminated structure.

TABLE 1 H₂ Firing con- tem- Crys- Ratio cen- per- Firing Latticeconstant tallite *3 *4 Raw Cs/ Rb/ tration ature time a-axis c-axis size*1 *2 *5 550 nm 1000 nm 1500 nm material W W [%] [° C.] [h] [Å] [Å] (nm)(nm) [%] [Pont] [%] [%] [%] Exam- Cs₂CO₃ 0.33 — 5 800 5.5 7.4071 7.618824 25 69.7 74.1 73.0 4.8 2.2 ple 1 and H₂WO₄ Exam- Cs₂CO₃ 0.31 — 5 8005.5 7.4100 7.6318 24 25 69.8 73.0 73.1 4.8 2.3 ple 2 and H₂WO₄ Exam-Cs₂CO₃ 0.35 — 5 800 5.5 7.4065 7.6203 24 24 69.8 73.6 73.1 5.0 2.4 ple 3and H₂WO₄ Exam- Cs₂CO₃ 0.37 — 5 800 5.5 7.4066 7.6204 24 25 69.8 73.673.1 4.8 2.3 ple 4 and H₂WO₄ Exam- Cs₂CO₃ and 0.33 — 5 800 5.5 7.40657.6193 24 25 71.7 70.0 74.9 5.1 2.4 ple 5 aqueous ammonium metatungstaresolution Exam- Cs₂CO₃ 0.21 — 5 800 5.5 7.4186 7.5825 24 24 69.4 69.372.1 7.2 5.1 ple 6 and H₂WO₄ Exam- Cs₂CO₃ 0.23 — 5 800 5.5 7.4184 7.582324 25 69.8 70.5 72.5 6.5 3.5 ple 7 and H₂WO₄ Exam- Cs₂CO₃ 0.25 — 5 8005.5 7.4165 7.5897 24 24 69.8 73.2 73.0 4.8 2.5 ple 8 and H₂WO₄ Exam-Cs₂CO₃ 0.27 — 5 800 5.5 7.4159 7.5919 24 25 69.5 72.4 73.1 4.8 2.2 ple 9and H₂WO₄ Exam- Cs₂CO₃ 0.29 — 5 800 5.5 7.4133 7.6002 24 25 69.9 72.873.3 4.8 2.3 ple 10 and H₂WO₄ Exam- Cs₂CO₃ 0.30 — 5 800 5.5 7.41187.6082 24 24 69.7 72.3 73.5 4.6 2.2 ple 11 and H₂WO₄ Exam- Cs₂CO₃ 0.33 —5 660 9.0 7.4068 7.6190 24 25 69.9 74.0 72.9 4.7 2.1 ple 12 and H₂WO₄Exam- Rb₂CO₃ — 0.33 5 800 5.5 7.3898 7.5633 24 25 69.6 69.5 73.2 8.0 2.4ple 13 and H₂WO₄ Exam- Cs₂CO₃ 0.03 0.3 5 800 5.5 7.3925 7.5730 24 2469.7 70.4 73.0 7.5 2.0 ple 14 and Rb₂CO₃ and H₂WO₄ Exam- Cs₂CO₃ 0.200.13 5 800 5.5 7.4026 7.6035 24 24 69.7 71.5 72.8 5.8 2.1 ple 15 andRb₂CO₃ and H₂WO₄ Exam- Cs₂CO₃ 0.25 0.08 5 800 5.5 7.4049 7.6083 24 2569.7 71.5 73.1 5.3 2.3 ple 16 and Rb₂CO₃ and H₂WO₄ Exam- Cs₂CO₃ 0.300.03 5 800 5.5 7.4061 7.6087 24 25 69.5 72.1 73.1 5.0 2.2 ple 17 andRb₂CO₃ and H₂WO₄ *1 Average particle size in a shielding body *2 Visiblelight transmittance *3 Difference of transmittance *4 Transmittance ateach wavelength *5 Maximum value-minimum value

TABLE 2 H₂ Firing Crys- concen- temper- Firing Lattice constant tallite*3 *4 Raw Ratio tration ature time a-axis c-axis size *1 *2 *5 550 nm1000 nm 1500 nm material Cs/W Rb/W [%] [° C.] [h] [Å] [Å] (nm) (nm) [%][Point] [%] [%] [%] Com- Cs₂CO₃ 0.11 — 5 800 5.5 7.4189 7.5825 24 2469.3 63.4 71.4 18.3 12.1 parative and Example 1 H₂WO₄ Com- Cs₂CO₃ 0.15 —5 800 5.5 7.4188 7.5826 24 25 69.4 66.1 72.3 17.1 10.9 parative andExample 2 H₂WO₄ Com- Cs₂CO₃ 0.39 — 5 800 5.5 7.4025 7.6250 24 25 69.667.2 71.5 19.2 9.5 parative and Example 3 H₂WO₄ Com- Cs₂CO₃ 0.21 — 5 4005.5 7.4198 7.5722 24 25 69.8 58.7 72.5 26.0 17.3 parative and Example 4H₂WO₄ Com- Cs₂CO₃ 0.23 — 5 400 5.5 7.4192 7.5729 24 25 69.9 59.9 72.125.0 15.2 parative and Example 5 H₂WO₄ Com- Cs₂CO₃ 0.33 — 5 800 5.57.4095 7.6312 9 9 69.9 66.4 71.5 18.5 9.0 parative and Example 6 H₂WO₄Com- Cs₂CO₃ 0.33 — 3 440 5.5 7.4072 7.6295 24 24 69.4 67.5 73.2 18.3 6.7parative and Example 7 H₂WO₄ Com- Cs₂CO₃ 0.33 — 5 800 5.5 7.4076 7.6130120 122 69.6 31.5 72.4 53.0 45.0 parative and Example 8 H₂WO₄ Com-Cs₂CO₃ 0.33 — 5 800 5.5 7.4092 7.6325 9 42 69.7 62.2 72.3 25.9 15.0parative and Example 9 H₂WO₄ *1 Average particle size in a shieldingbody *2 Visible light transmittance *3 Difference of transmittance *4Transmittance at each wavelength *5 Maximum value-minimum value

INDUSTRIAL APPLICABILITY

The present invention is suitably applied to construction fields such asbuildings, offices, and general houses, transportation fields such asvehicles, agricultural fields such as vinyl sheets, telephone box, carport, show window, lighting lamp, transparent case, fiber etc., when anear-infrared shielding effect is imparted thereto by using thenear-infrared shielding material fine particles.

The invention claimed is:
 1. A near-infrared shielding material fineparticle dispersion body in which near-infrared shielding material fineparticles are dispersed in a solid medium, wherein the near-infraredshielding material fine particles are composite tungsten oxide fineparticles containing a hexagonal crystal structure, a lattice constantof the composite tungsten oxide fine particles is 7.4031 Å or more and7.4186 Å or less on the a-axis, and 7.5830 Å or more and 7.5950 Å orless on the c-axis, and a particle size of the near-infrared shieldingmaterial fine particles is 100 nm or less.
 2. The near-infraredshielding material fine particle dispersion body according to claim 1,wherein the particle size of the near-infrared shielding material fineparticles is 10 nm or more and 100 nm or less.
 3. The near-infraredshielding material fine particle dispersion body according to claim 1,wherein the composite tungsten oxide fine particles are expressed by ageneral formula M_(x)W_(y)O_(z), wherein M element is one or moreelements selected from the group consisting of H, He, alkali metal,alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co,Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, TI, Si, Ge, Sn, Pb,Sb, B, F, P, S, Se, Br, Te, Ti, Mb, V, Mo, Ta, Re, Be, Hf, Os, Bi, andI, W is tungsten, O is oxygen, and satisfying 0.20≤x/y≤0.37, and2.2≤z/y≤3.0.
 4. The near-infrared shielding material fine particledispersion body according to claim 3, wherein the M element is one ormore elements selected from Cs and Rb.
 5. The near-infrared shieldingmaterial fine particle dispersion body according to claim 1, wherein asurface of each near-infrared shielding material fine particle is coatedwith an oxide containing one or more elements selected from Si, Ti, Zrand Al.
 6. The near-infrared shielding material fine particle dispersionbody according to claim 1, wherein the solid medium is resin or glass.7. The near-infrared shielding material fine particle dispersion bodyaccording to claim 6, wherein the resin is one or more kinds selectedfrom polyethylene resin, polyvinyl chloride resin, polyvinylidenechloride resin, polyvinyl alcohol resin, polystyrene resin,polypropylene resin, ethylene vinyl acetate copolymer, polyester resin,polyethylene terephthalate resin, fluororesin, acrylic resin,polycarbonate resin, polyimide resin, and polyvinyl butyral resin.
 8. Anear-infrared shielding body, wherein the near-infrared shieldingmaterial fine particle dispersion body of claim 1 is formed into any oneselected from a plate shape, a film shape, and a thin film shape.
 9. Anear-infrared shielding laminated structure, wherein the near-infraredshielding material fine particle dispersion body of claim 1 is presentbetween two or more laminated plates selected from a plate glass, aplastic plate, and a plastic plate containing fine particles having asolar radiation shielding function.
 10. A method for producing anear-infrared shielding material fine particle dispersion body,comprising: a first step of producing composite tungsten oxidecontaining a hexagonal crystal structure expressed by a general formulaM_(x)W_(y)O_(z), wherein M element is one or more elements selected fromthe group consisting of H, He, alkali metal, alkaline earth metal, rareearth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag,Au, Zn, Cd, Al, Ga, In, Ti, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te,Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O isoxygen, and satisfying 0.20≤x/y≤0.37, and 2.2≤z/y≤3.0; a second step ofproducing composite tungsten oxide fine particles by mechanicallypulverizing the composite tungsten oxide obtained in the first step, inwhich a lattice constant in the hexagonal crystal structure is 7.4031 Åor more and 7.4186 Å or less on the a-axis, and 7.5830 Å or more and7.5950 Å or less on the c-axis, and a particle size is 100 nm or less;and a third step of dispersing in a solid medium the composite tungstenoxide fine particles obtained in the second step, to obtain anear-infrared shielding material fine particle dispersion body.
 11. Themethod for producing a near-infrared shielding material fine particledispersion body according to claim 10, wherein the solid medium is resinor glass.
 12. The method for producing a near-infrared shieldingmaterial fine particle dispersion body according to claim 11, whereinthe resin is one or more kinds selected from polyethylene resin,polyvinyl chloride resin, polyvinylidene chloride resin, polyvinylalcohol resin, polystyrene resin, polypropylene resin, ethylene vinylacetate copolymer, polyester resin, polyethylene terephthalate resin,fluororesin, acrylic resin, polycarbonate resin, polyimide resin, andpolyvinyl butyral resin.
 13. The method for producing a near-infraredshielding material fine particle dispersion body according to claim 10,wherein the third step further includes a fourth step of forming thenear-infrared shielding material fine particle dispersion body into anyone selected from a plate shape, a film shape, and a thin film shape.14. The method for producing a near-infrared shielding material fineparticle dispersion body according to claim 13, wherein the fourth stepincludes a step of forming the near-infrared shielding material fineparticle dispersion body on a substrate surface.
 15. A method forproducing a near-infrared shielding laminated structure, including afifth step of sandwiching the near-infrared shielding materialdispersion body obtained in the method for producing a near-infraredshielding material fine particle dispersion body of claim 13, betweentwo or more opposed transparent substrates selected from a sheet glass,a plastic, and a plastic containing fine particles having a solarshielding function.